I was hoping someone might be able to help me with this. I recently (about 3 weeks ago) got a used Samigon 28-80mm f/3.5 zoom lens for my OM-1. It is giving me some vignetting problems though. It is relatively minor vingetting, but it is cutting off the corner maybe 1% on most of the pictures. My other two lenses a 50mm f/1.8 and a 135mm f/2.8 are not giving me any problems with this.
I am guessing this is an issue with the lense itself. Does anyone know of a way to correct this? Would stopping it down an F-stop or two maybe correct this (I have heard a rumor or two that this works for some lenses)? Is there a posibility that it is because of a buildup of dirt around the edge of the lense??? I have cleaned it fairly well, but the very very corners of the lense do appear somewhat dirty...I just haven't been able to get a cloth in there very well to clean the very edges. It does seem like some of the pictures with the lens stopped down 3 or 4 stops show no vignetting...of course this is not an ideal way to be using the camera if I have to be using f/16 or f/22 all the time (especially lower light).
Also can anyone recommend a fairly decent medium telephoto zoom for the camera body? Preferably in the 70-150 or 80-200mm range? Also if I can't correct for the vignetting on this lense can anyone recommend another good 28-70, 28-80, 35-70 or 35-80mm lense that works well?
Here is a recent picture taken with the camera hopefully demonstrating the extent of the vignetting. You can see the vignetting at the top left corner.